This invention relates to a solar energy collector utilizing air or other fluid as the heat transfer media.
The initial cost and the efficiency of such collectors have been the major problems encountered in constructing a practical collector.
Collector units have been proposed employing flat plates disposed to face the sun and over which air flows in contact with the plates to pick up heat therefrom and transmit the same to a storage unit or to a point of use.
Furthermore, it has been known to apply a black paint to a flat-plate collector to provide a highly efficient selective surface giving good absorptance of solar energy.
In systems utilizing air as the heat pick-up media, there is a need for considering the optimum air velocity for turbulent air flow in contact with the surface of the heated flat-plate collector, and controlling the air flow in accordance with the available heat. In general the higher the temperature of the flat plate collector the higher air velocity may be employed for a given output air temperature, and/or the higher will be the output air temperature for a given velocity of air.
Since the sun does not always shine constantly upon the collector, there may be frequent times in which the temperature of the flat-plate collector drops because of lack of solar energy input.